Adjective Clauses
ELC Study Zone
This is such a useful page for so many things--this link is for their adjective clause page with a lesson and exercises.
Grammar Quizzes
The name of this site is a little confusing--it actually has more than quizzes--it has great lessons and exercises.
Restrictive/Non-restrictive handout
Nice PDF explanation with exercises and answer key.
Adjective Clause Powerpoint